A semiconductor diode having a P-N junction is an electronic device which allows current to pass when a forward biased voltage is applied and which blocks current when a reverse biased voltage is applied. The P-N junction includes a P-type semiconductor and an N-type semiconductor which are in contact with each other. When reverse biased, the voltage across the junction can be increased without significantly increasing a leakage current through the diode until the breakdown voltage for the junction is reached. Once the reverse biased voltage exceeds the breakdown voltage, the current through the reverse biased diode suddenly increases. Accordingly, there is a need in the art to increase the breakdown voltage of a reverse biased P-N junction diode.
In a typical planar diffusion method for producing a P-N junction diode, a cylindrical junction is formed by diffusing a dopant through an oxide window. The resulting junction generates a greater electric field than that produced by an ideal planar junction because of curvature at the edge of the junction. As a result, the breakdown voltage of a cylindrical junction diode is significantly lower than that of an ideal planar junction diode.
A conventional junction termination extension ("JTE") is a termination which reduces the concentration of the electric field in a cylindrical junction diode. The JTE structure has a lateral low dose doping region at the edge of the P-N junction. The maximum electric field generated by the junction is reduced because the JTE structure extends a depletion region into the low dose region. The formation of the conventional JTE structure, however, may require an additional masking procedure to extend the low dose region. This additional masking procedure may increase the cost and complexity of the fabrication of the diode.